Slide 1: Welcome to today s The Nitrogen Cycle presentation, where we ll be talking to you about the importance of nitrogen in our environment.

Transcription

1 Slide 1: Welcome to today s The Nitrogen Cycle presentation, where we ll be talking to you about the importance of nitrogen in our environment. 1

2 Slide 2: Barnegat Bay, like many coastal areas in the country, is undergoing water quality problems that affect both its use and ecology. After many years of study, the biggest issue affecting the Bay is over enrichment by nutrients, primarily nitrogen, from surface runoff. Approximately half of the nitrogen loads to Barnegat Bay originate from surface runoff. Other sources of nitrogen include atmospheric deposits and seepage from groundwater. Even though nitrogen is a naturally occurring substance, in excessive amounts problems can occur. Increased nitrogen leads to eutrophication and hypoxia (lowered dissolved oxygen), increased harmful algal blooms, loss of submerged aquatic habitat, altered benthic communities, and loss of fisheries. These impacts can have far reaching effects on not just ecological habitat but also on local economies that rely on fishing, shore tourism, and boating. 2

3 Slide 3: Urban lands can help create excess stormwater runoff. Urban areas are not restricted to major cities or urban centers. They represent any of the developed lands located within an area. These areas include commercial and residential properties, and those areas associated with the underlying infrastructure. Transportation corridors, such as major highways, roads and rail networks, utilities, such as power lines and stormwater basins, are include in this category. Image Credit: Rutgers Cooperative Extension of Ocean County 3

4 Slide 4: These developed lands alter the function of all components of the hydrologic cycle by increasing the amount of impervious cover in our landscape. Impervious cover is any hard surface, such as roads, rooftops, and parking lots, that do not allow stormwater to soak into the ground. The percent impervious cover in an area gives us an indication of what percentage of stormwater becomes runoff, gets evaporated, or gets absorbed back into the soil. These four diagrams show these changes as an area goes from a natural condition (0% imperviousness) to a fully built environment (100% imperviousness). By increasing the amount of impervious cover in a watershed and losing natural ground cover, evaporation decreases, infiltration decreases, and runoff increases. This can lead to a larger volume of water that floods local areas and causes faster runoff flows which can carry nitrogen and erode natural lands and streambanks. The Barnegat Bay Watershed landscape is at about 7.5% impervious cover. The hydrologic cycle for the Bay s watershed is presumed to be similar to the upper right diagram. Image Credit: United States Environmental Protection Agency 4

5 Slide 5: A variety of water quality impacts are due to the accumulation of pollutants on the hard surfaces. These pollutants come from human activities such as yard care (debris such as leaves and grass clippings; nutrients from fertilizers; pesticides applied to remove pests), dog walking (potential for bacterial contamination), illegal activities (littering and dumping), or car driving (metals from brake wear, oil, and fluids from leaking pans and hoses). When a rain storm moves through an area the runoff picks up these accumulated pollutants and carries them to local waterways. 5

6 Slide 6: Nitrogen is an essential nutrient for the growth of plants and animals. It is especially important in the creation of proteins. Nitrogen can get into the environment from lawn fertilizer, animal waste, decomposing organic matter, nitrogen fixing bacteria, fossil fuel emissions, and lightning. Nitrogen comes in many different forms in the environment. Nitrogen gets transformed into different forms as it moves through the air, water, and soil. Nitrate (NO3) is the form most usable by plants for growth. An excess amount of nitrate in the environment can cause uncontrolled growth of plant material. This can be seen in coastal areas as algal blooms (population explosions of microscopic algae). Image Credit: 6

7 Slide 7: There are methods to control and reduce the amount of nitrogen that gets into the environment. One method is the use of green infrastructure. Green infrastructure is an approach to stormwater management that is cost effective, sustainable, and environmentally friendly. It uses soil and plants to manage the quantity and quality of stormwater. Green infrastructure projects capture, filter, absorb, and reuse stormwater to maintain or mimic natural systems and treat runoff as a resource. Image Credit: Rutgers Water Resources Program 7

8 Slide 8: There are many types of green infrastructure projects. Vegetated filters, pervious paving, bioretention basins, and constructed wetlands are types of green infrastructure. Each type of green infrastructure has been studied to determine its effectiveness in reducing pollutants in stormwater. Here we see a table outlining the effectiveness of different stormwater management projects and how well they reduce the nutrients, total phosphorus (TP) and total nitrogen (TN). While many of these projects can reduce TP well, they are not as effective at reducing TN. Image Credit: New Jersey Department of Environmental Protection 8

9 Slide 9: To create a more effective means of removing nitrogen from stormwater, the University of New Hampshire s Stormwater Center (UNHSC) has established guidelines for the design of subsurface gravel wetlands as a type of green infrastructure. Results from their work indicate that such gravel wetlands can achieve a median annual removal of at least 95% of NO3, and TP removal was 55%. 9

10 Slide 10: The subsurface gravel wetland system is a combination of a surface marsh and a subsurface gravel bed. Pollutants are treated through settling, both uptake and filtration by vegetation, and chemical transformation in the subsurface gravel bed, specifically denitrification. Image Credit: University of New Hampshire Stormwater Center 10

11 Slide 11: We have partnered with Georgian Court University on a project to design and install subsurface gravel wetlands on their campus for research purposes. The subsurface gravel wetlands were paid for through a grant from the New Jersey Department of Environmental Protection. The project involves installing four differing designs of subsurface gravel wetlands and testing each design to see which is the best option for future work in New Jersey. The four designs vary by the depth and type of subsurface bed material used in their construction. Image Credit: Rutgers Cooperative Extension of Ocean County 11

12 Slide 12: The study methods we used involve collecting stormwater from storm events at the inlet and outlets of each subsurface gravel wetland design. Autosamplers were used for collection of water samples. The water samples were then analyzed for nutrients (nitrogen and phosphorus series) and total suspended solids (TSS). Vegetation was sampled for growth (density, height, species richness) and underwent tissue analyses for nutrients to determine plant uptake of nitrogen. Sampling occurred from May 2016 to now (May 2018). 12

13 Slide 13: The schematic seen here shows the location of each sampling point: one inlet and four outlets. Image Credit: Rutgers Cooperative Extension of Ocean County 13

14 Slide 14: To determine the effectiveness of the subsurface gravel wetland designs pollutant removal is calculated as percent removal (%R) of the measured target analytes (TA) in the runoff. All losses from the system through the various physical, chemical and biological processes are lumped together and the %R calculated as the amount of pollutant coming in minus the amount going out, then divide that by the amount coming in. This number is multiplied by 100 to get a percentage. We have a worksheet with the data collected thus far, that we would like you to work on to help us determine which of the four designs was the most effective using this formula. 14